LASERS CERTIFICATION Practice Test Exam Questions and
Answers Graded A+ 2025/2026
What states can the active medium be in? - solid, gas, semiconductor
What type of active medium is used in Er: YAG? - solid state using crystal
matrix (erbium laced yttrium, aluminum and garnet)
What type of gas is used when the active medium is sealed in an air tight
chamber? - CO2
Diode lasers have what type of active medium? - semiconductor
what photons form the laser? - light that leaks from the output coupler
Stimulated emission: - atoms of the active medium are stimulated to a
higher energy level--> released as a photon as the atom returns to a more
stable lower energy level.
Amplification - Released photons can go on to stimulate more atoms in the
crystal, thus producing more photons
Energy density depends on what 3 things? - energy, divergence (tendency
of a laser beam to spread outward=laser beam diameter increases), and
distance
Energy is measured in ______ - Joules (millijoules)
Power is ______ and is measured in _______ - rate of doing work, or
energy used over a period of time and is measured in Watts (J/sec)
Frequency is measured in _____. - Hertz ( laser pulses/sec)
What is the most important variable dictating how the laser beam will
interact with the target tissue? - Peak Power
Define Peak Power: - power level in each individual laser pulse, however it
is not visible to the operator
Describe Peak Power in the 3 types:
, 1) Continuous
2) Gated
3) Free running pulsed - 1) the peak power equals the average power
displayed
2) Average power is half of peak power
3) Low Average power, very high peak power
What are the two basic forms of pulsed laser modes? - Gated wave
Free running pulsed
How is the gated wave pulse created? - created with a shutter that blocks
the laser beam from reaching the handpiece and target tissue at varying
speeds: the laser is on constantly but the shutter device blocks the light
from transmitting. (example: flashlight moving hand in front of it)
How is the Free running pulse created? - Not on constantly, but emit
photons in powerful bursts of energy measured in millionths of seconds.
(example: turning flashlight on and off)
Which lasers operate in continuous mode? (can be mechanically turned
into a gated mode when a shutter is used) - CO2, Diode
Which lasers operate in free running pulsed mode? - Nd:YAG, Erbium
lasers
Shorter pulses ______ peak power (increase or decrease?)
Which laser uses shorter pulses? - increases
Hard tissue lasers
Define Thermal relaxation - ability of the target tissue to absorb heat
produced by laser interaction
When does thermal relaxation occur? soft or hard tissue? - ONLY occurs
during soft tissue procedures
Describe thermal relaxation in the three types of lasers. - -Continuous
mode:
No thermal relaxation (damaging heat can build in the tissue quickly)
-Gated wave mode:
Answers Graded A+ 2025/2026
What states can the active medium be in? - solid, gas, semiconductor
What type of active medium is used in Er: YAG? - solid state using crystal
matrix (erbium laced yttrium, aluminum and garnet)
What type of gas is used when the active medium is sealed in an air tight
chamber? - CO2
Diode lasers have what type of active medium? - semiconductor
what photons form the laser? - light that leaks from the output coupler
Stimulated emission: - atoms of the active medium are stimulated to a
higher energy level--> released as a photon as the atom returns to a more
stable lower energy level.
Amplification - Released photons can go on to stimulate more atoms in the
crystal, thus producing more photons
Energy density depends on what 3 things? - energy, divergence (tendency
of a laser beam to spread outward=laser beam diameter increases), and
distance
Energy is measured in ______ - Joules (millijoules)
Power is ______ and is measured in _______ - rate of doing work, or
energy used over a period of time and is measured in Watts (J/sec)
Frequency is measured in _____. - Hertz ( laser pulses/sec)
What is the most important variable dictating how the laser beam will
interact with the target tissue? - Peak Power
Define Peak Power: - power level in each individual laser pulse, however it
is not visible to the operator
Describe Peak Power in the 3 types:
, 1) Continuous
2) Gated
3) Free running pulsed - 1) the peak power equals the average power
displayed
2) Average power is half of peak power
3) Low Average power, very high peak power
What are the two basic forms of pulsed laser modes? - Gated wave
Free running pulsed
How is the gated wave pulse created? - created with a shutter that blocks
the laser beam from reaching the handpiece and target tissue at varying
speeds: the laser is on constantly but the shutter device blocks the light
from transmitting. (example: flashlight moving hand in front of it)
How is the Free running pulse created? - Not on constantly, but emit
photons in powerful bursts of energy measured in millionths of seconds.
(example: turning flashlight on and off)
Which lasers operate in continuous mode? (can be mechanically turned
into a gated mode when a shutter is used) - CO2, Diode
Which lasers operate in free running pulsed mode? - Nd:YAG, Erbium
lasers
Shorter pulses ______ peak power (increase or decrease?)
Which laser uses shorter pulses? - increases
Hard tissue lasers
Define Thermal relaxation - ability of the target tissue to absorb heat
produced by laser interaction
When does thermal relaxation occur? soft or hard tissue? - ONLY occurs
during soft tissue procedures
Describe thermal relaxation in the three types of lasers. - -Continuous
mode:
No thermal relaxation (damaging heat can build in the tissue quickly)
-Gated wave mode:
